How and on what to implement the administration of n machines via the Internet?

Question

FreeBSD

There are n cars. Need to run openvpn remotely on xp machine if needed. with return ip to admin. All over the Internet. For further help via Ultravnc. There is no way to always keep vpn running. it is often difficult for a PC operator to start openvpn and report ip.
Cars on xp.
There is a server on freebsd. (aka vpn) white ip.
There is an admin on Windows. (or anything else) (port forwarding is possible.)
It is necessary for the admin to remotely give commands to clients to start openvpn.
Those. the client connected to the server (server may not be on Linux) receives commands.
Connecting to clients is not easy to learn due to the inability to configure forwarding, dmz, etc. everywhere.

Answer 1

Head-on solution - TeamViewer
In general, the task statement is blurry - one way or another, you either need to maintain a permanent connection initiated by the client, or request a label on the scheduler and respond to it - automate this will help, for example, nnCron
The label can be, for example, the availability of a file on the http server by url (for each car)

Answer 2

You can look in the direction of dyn dns and hang some kind of incoming handler.
But it's best to always keep vpn simple.

Answer 3

You need to install openvpn on the gateway and configure the routing correctly, then there will not be a bunch of vpn clients, the vpn will always be running. Further to all clients to add static dhcp of a liza. You will know their ip and can connect at any time.

Answer 4

What prevents you from always keeping openvpn connected?
I've always connected to the machine and does not interfere well, in any way.

Answer 5

Set the client - the Openvpn client, set the server for yourself.
At the client you register in a config - to keep connection. If interested, I can look at the parameter, I don’t remember offhand. But in the end, in the event of a disconnection, loss of the Internet, the client will automatically connect to you when the Internet appears.
Forcing you to tell you the IP address of the client is optional. Firstly, you can see it in the log, and secondly, assign the static to the client. And it will have a permanent IP.
Well, or use teamwiever, as we wrote earlier. Set a permanent password, and autorun when you turn on the computer. And there will be no need to pull people at all.

Answer 6

Thank you. But all of the above is already known. teamviewer is out of license.
Openvpn is already installed, but it only starts on demand now.
It is impossible to keep vpn because on all machines there is software that connects to a neighboring (local) wheelbarrow. (subdbd, etc.)
Openvpn is already installed, but it only starts on demand now.
And when the vpn is up, something happens to the routes. And the client software does not work. But that's not even the worst thing. According to tests, about 10 connections load either the channel or the server in such a way that it is not possible.

Answer 7

Look towards IPv6, the protocol allows you to work on top of IPv4 + it is also a NAT killer, i.e. if there is a nat on the router, then ipv6 does not interfere in any way.
Or yes, install openvpn on the gateway that will share the entire network for you when connected, then users will not need to be pulled. I can advise you to deploy a Zentyal server as an option, openvpn is already assembled there + a lot of things.

Answer 8

Take a look at LiteManager, it will definitely work under Win